Articulated railway cars designed for carrying highway truck trailers and/or containers are well known. In the usual arrangement, an articulated car consists of preferably five interconnected car units in which the remote ends of the end units have standard trucks and have standard couplers for coupling with couplers of other cars in a train makeup. The interior ends of the end car units and the other three car units have articulated connections for close coupling to accommodate one truck which spans and supports the ends of two adjacent car units.
Fuel conservation and environmental concerns require that these railway cars be designed with minimum weight but without sacrificing structural strength and stability for carrying fully loaded containers and/or truck trailers. In order to reduce car weight, manufacturers of some cars have eliminated a support structure for preventing container lading from falling to the tracks in the event of a container floor failure. The lack of such support structure is highly undesirable.
Manufacturers have also reduced car weight by reducing the height, depth and web and flange thicknesses of structural members such as the center sill and cross-bearers. This size downgrading of structural members has the adverse effect, however, of increasing axial and bending stresses in, and deflection of, load bearing structural members, particularly when a car unit is loaded with two containers or trailers end-to-end. This type of loading subjects the center sill member to a very high bending moment adjacent to its midpoint. Therefore, the center sill member must be increased in size or carefully designed and constructed to avoid undue deflection of the center sill.
Dual purpose cars designed for carrying both containers and highway truck trailers typically have wheel pans or decks for supporting the wheels of a trailer, and container brackets, mounts or locks for securing the lower edges of containers. At least two of the container locks are typically located on or adjacent to the wheel pans of the car. In order to prevent interference between the container locks and the wheels of a trailer, it is known in the prior art to use pivotable or stowable container locks on the wheel pans. When not in use, pivotally supported locks can be rotated to a stowed position below the wheel deck surface. For example, see the pivotally mounted container locks disclosed by Hesch, et al., in U.S. Pat. No. 5,052,868, issued Oct. 1, 1991, entitled "All Purpose Car."
Although useful in preventing interference with the wheels of a trailer on the wheel pans, pivotable container locks of the prior art suffer from an inherent disadvantage. These existing locks have the tendency, when erected for receiving a container, to inadvertently move into a horizontal or stowed position before a container can be installed on the lock. Once a container is installed on the lock, the container holds the lock in the upright position. However, prior to loading the container, the lock is not positively retained in its upright position and can be inadvertently moved to the stowed position when engaged in the wrong direction, such as by the container.
Prior dual purpose articulated cars also have limited capacity for carrying the longer highway truck trailers that are increasingly being used by transporters. Trailers and containers longer than 48 feet cannot be carried on existing car units without sacrificing carrying space on an adjacent car unit.
Consequently, a need exists for a lightweight railway car for transporting containers, highway truck trailers and similar types of cargo with improved structural resistance to deflection when carrying fully loaded and also providing back-up support for container floors which occasionally rupture from the weight of the container lading. A need also exists for an articulated railway car with car units that can each accommodate both containers and highway truck trailers up to 53 feet in length without loss of carrying capacity on adjacent car units. A further need exists for a means for securing stowable container locks in their upright position prior to and during the loading of a container thereon.